The package allows LaTeX users who use the TX fonts to select
the shapes (italic or upright) for the Greek lowercase and
uppercase letters. Once the shapes for lowercase and uppercase
have been selected via a package option, the \other prefix
(e.g., \otheralpha) allows using the alternate glyph (as in the
fourier package). The txgreeks package does not constrain the
text font that may be used in the document.